The primary objective of the research outlined in this proposal is to obtain new information concerning the role of vitamin A in vision using a mosquito, Aedes aegypti, as the experimental animal. Initial experiments are intended to show the localization of vitamin A within the photoreceptor cells. Follow-up experiments are designed to show organelle association of vitamin A as it is incorporated into the photoreceptor cell and utilized in the visual process. In addition, the functional capabilities of single photoreceptor cells, as measured by the intracellular electroretinogram (ERG), will be investigated under conditions of vitamin A deficiency and availability. Several secondary objectives are associated with this research. First, it has previously been suggested that vitamin A is transferred from adult to offspring in some insects. Experiments will be designed to test whether such a transfer does occur. Second, very little is known about the systemic role and the metabolism of vitamin A in invertebrates. Experiments will be done to determine which tissues and organs are involved in the uptake of this vitamin or its precursor from the environment, and which tissues or organs are involved in its subsequent metabolism. A comparison will then be made to similar processes in the vertebrates. Finally, the incorporation of the tritiated amino acid into the photoreceptor cells will be examined and compared with that of tritiated vitamin A. BIBLIOGRAPHIC REFERENCES: Respiratory Response of Aquatic Stages of Aedes aegypti Exposed to Water Soluble Gasoline Fractions. (with William O. Berry) Amer. Zool. 15: 716, 1975 (Abstract). Changes in Volume of the Rhabdom in the Compound Eye of Aedes aegypti L. (with Bruce Clarin) J. Exp. Zool., 1976, in press.